Flash lamp



L. V. MCCARTY Jan. 7, -1964 FLASH LAMP Filed April 4. 1961 l: CONBUST/BL' 6W5 f4 am cy /V N) MM /V N) C2 N2 Bar/0 .wu :vmwd T n @emr M e O\ VE .mw

United States Patent O 3,116,623 FLASH LAMP Lewis V. McCarty, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Filed Apr. 4, 1961, Ser. No. 100,578 2 Claims. (Cl. 67-31) This invention relates in general to tlash lamps of the type comprising a sealed radiation transmitting envelope containing a quantity of combustible light producing material and la combustion support-ing medium such as an oxygenous gas which enters into a reaction with the combustible material with the resulting emission off an instantaneous liash of actinic light of high intensity. More particularly, this invention relates to a liash lamp containing the combustible material, cyanogen gas, which with oxygen, reacts to provide the source of actinic light.

'l'he combustible material used in present-day cornmercial ash lamps is a magnesium, aluminum or zirconium alloy foil or filament. The most objectional feature of a lamp of this type for use in color photography is that the spectral distribution of the light emitted is very dissimilar from ordinary sunlight. Thus, the lamp must either be equipped with a lter coating or used with special lilm. However, prior to this invention, the only practical lamps were based on metal foils, filaments or powders which radiated suicient light for photographic purposes because of the liquid droplets of metal oxide rformed in the high temperature reaction. While flash lamps have been customarily made with a foil or lilament till-ing because of good radiating eiciency sorne work has been done previously `towards developing a gas filled tlas'h lamp. For example, the Van Liempt et al., Patent No. 2,013,371, discloses the use tof several cornbustible gas mixtures for use in flash lamps. However, such lamps have not hitherto been practical mainly because of low light output, when used as previously disclosed, because most hot gases are relatively poor radiators or light as Compared with the liquid droplets of metal formed in the actinic reaction of a metal foil or iilament with a gas, and also because of poor storage life during which the reactant materials may attack the lead-in wires. The aforesaid deficiencies are overcome by a flash lamp constructed in accordance with the instant invention.

An object of this invention, therefore, is to provide a Iflash lamp containing a gaseous combustible mixture including certain ratios of cyanogen and oxygen wherein excited particlesl of the .gaseous mixture act as eliicient radiators of light comparable to the solid or liquid p-art-icles present in the combustible material illed flash lamps.

Since ilash lamps are made for only a single use and thereafter must be thrown away, another `object of this invention is to provide such a flash lamp which is practical and economical to produce.

Still another object of this invention is to provide a ash lamp having a short Iduration of light output and emitting light having a spectral distribution comparable to outdoor light on a sunny day.

In accordance with the above-mentioned objects this invention relates to a tash lamp comprising a sealed glass bulb iilled with a combustible mixture of cyanogen and oxygen, the cyanogen-oxygen ratio being in the range between 1 and 1.4 together Iwit-h means for igniting said mixture.

Further objects and advantages of the invention will appear from the following detailed description of the invention and from the accompanying drawing.

In the drawing, FIG. 1 is a view in elevation of a flash lamp comprising the invention and FIG. 2 is a graph showing the effects of varying the cyanogen-oxygen natio on the light intensity.

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Referring to the drawing, a flash lamp according to the invention comprises a sealed glass envelope 4 cemented to a metal base 5. Ignition means 6 for igniting the combustible gas filling comprises lead wires 8, 9 electrically connected to base 5 and i-ts `associated center contact 5' together with :a filament 10 connected across lead wires 8, 9. The combustible gas is readily ignitable at the temperature attained by the lilament 10, hence primer material, such 'as used fin present-day commercial lamps, is not necessary -for ignition purposes. However, pr-irner beads 11 may be provided so as to control the time of ignition. Primer beads 11 may consist of a mixture of zirconium, potassium perchlorate and magnesium bonded together with a suitable binder such as 2 to 5% solution of nitrocellulose in amyl acetate.

The combustible gas mixture comprises cyanogen and oxygen reacting generally in the following manner:

If sutiicient oxygen is furnished, the mixture will also react as follows:

While Reaction 2 releases more energy than Reaction 1 since in reality it involves further oxidation of carbon monoxide which is produced according to the Reaction 1, it might be believed that stoichiometric mixtures for producing the Reaction 2 would produce the most light. However, in spite of the lesser .amount of energy released, it has been found that Reaction 1 radiates more light. This unusual result will be observed from an inspection of the data given below and shown graphically in FIG. 2 ofthe drawing. This phenomenon may be explained by the great stability of the carbon monoxide molecules produced by Reaction 1 which results in a higher reaction temperature. Whatever the explanation, Reaction 1 is found to radiate approximately ten times as much light as Reaction 2. A further increase in light emission occurs on going to the cyanogen rich mixtures and the optimum mixture of about 47% oxygen and 53% cyanogen radiates approximately forty-seven times as much light as the stoichiometry for Reaction 2 as shown in the following table:

Light Emission Data for C2N2/O2 Reaction C2N2 Press., O2 Press., Percent, Percent, Ratio, Lumens mm. mm. CzNz O2 CzNz/Og at Peak This data is represented graphically in FIG. 2 ot the drawing. As shown in curve 13, the light emitted from the cyanogen-oxygen mixture increases greatly at a ratio of approximately 1.4 and the light intensity further increases as 4the natio approaches approximately 1.15. Then at the stoichiometry of Reaction l noted above, tha-t is,

as a cyanogen-oxygen ratio of 1.0 is approached, the light intensity is 'approximately 1/2 of intensity of the optimum mixture. When tsutiicient oxygen is provided for the stiochiometry of Reaction 2, that is, where the cyanogenoxygen ratio is .5 the light intensity is approximately 1/47 of the light output from the optimum mixture, that is, where the cyanogen-oxygen ratio is approximately 1.15. Curves 14, 15 and 16 show the same optimum mixture to be necessary as additional amounts `of combustible gas are added by increasing the lling pressure of the mixture in the glass envelope 4. The light intensity of the optimum mixture would appear to be relatively independent of the total pressure within the bulb, and is only dependent on the provision of an excess o-f cyanogen gas molecules which are excited by the reaction -to radiate light.

The burned lamps have a carbon residue in them, and it is believed that a part of the excess cyanogen decomposes to form carbon. Carbon vapor as such or as cyanogen radicals in the presence of excessive nitrogen at the high temperatures produced by the reaction act as a radiating gas performing a function similar to the molten droplets in a conventional metal foil or lament flash lamp. The addition of other carbon vapor producing gases, such as benzene and acetylene, -to a mixture containing equal amounts of cyanogen and oxygen lends some Isupport to this belief since improved light emission results. The eect of selected foreign gases which produce radicals subject to being excited is as follows:

E jfect of Foreign Gases on the Lig/1t Emission. of the CZNZ/Oz Reaction Mm; Added Gas LCZNQ Press., O2 Press. mm., Peak Light Inmm. tensity Lumens 302. 6 200A G 470, 000 302. 1 300. 3 500, 000 302. 1 300. 1 G00, 000 302. 299. 4 500, 000 302. 3 300. 3 500, 000 302. 300.0 350, 00() 300. 290. 2 240, 000

As will be noted, the effect of these carbon vapor producing gases inuence light emission similarly to the manner of excess cyanogenbut not to as large an extent. The chief dilerence seems to be that the hydrogen produced at dame temperature of the reaction is dissoeiated while the nitrogen which is produced from the pure cyanogen-oxygen reaction is largely combined as molecular nitrogen. Since large amounts of energy are needed to dissociate hydrogen the maximum ame temperature drops and the optimum mixture is not as good a radiator as mixtures containing simply excess cyanogen.

An important advantage of a ilash lamp comprising this invention is the color balance of the cyanogen-oxygen flash. lThe spectra of the flashes show cyanogen bands beginning at 4606, 4216 and 3883 angstroms and swan bands for the C2 molecule at 5635, 5165, 4737 and 4382 angstroms and a relatively rich but less intense spectrum at longer wavelengths. While this appears to be a rather banded structure, colored photographs have been made using ordinary outdoor color lm with cyanogen-oxygen flashes as the sole source of illumination with very satisfactory results.

Although a preferred embodiment of my invention has been disclosed, it lwill be understood that the invention is not to be limited to the specific construction and arrangement of parts shown and that they may be widely modified within the spirit and scope of this invention as defined by the appended claims.

What I claim as new and des-ire to secure by Letters Patent of the United States is:

1. A llash lamp comprising a sealed envelope containing a gaseous combustible mixture of cyanogen and oxygen wherein the cyanogen-oxygen ratio is between 1 and 1.4.

2. A Hash lamp comprising a sealed envelope containing a gaseous combustible mixture of cyanogen and oxygen wherein `the cyanogen-oxygen ratio is approximately 1.15.

References Cited in the tile of this patent UNITED STATES PATENTS 2,013,371 Van Liempt et al. Sept. 3, 1935 

1. A FALSH LAMP COMPRISING A SEALED ENVELOPE CONTAINING A GASEOUS COMBUSTIBLE MIXTURE OF CYANOGEN AND OXYGEN WHEREIN THE CYANOGEN-OXYGEN RATION IS BETWEEN 1 AND 1.4. 